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Evaluation of applications over an intranet

Evaluation of applications over an intranet. Intranet architecture. 50 Unix Workstation. File server 2. Lan 2 10 Mbps Eth. Lan 3 10 Mbps Eth. R2. File server 1. Web server. 100 Windows NT clients. FDDI 100 Mbps Lan 5. 120 Windows NT clients. File server 3. R3. R1.

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Evaluation of applications over an intranet

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  1. Evaluation of applications over an intranet

  2. Intranet architecture 50 Unix Workstation File server 2 Lan 2 10 Mbps Eth Lan 3 10 Mbps Eth R2 File server 1 Web server 100 Windows NT clients FDDI 100 Mbps Lan 5 120 Windows NT clients File server 3 R3 R1 Lan 1 10 Mbps Eth R4 Lan 4 16 Mbps TR 100 Windows NT clients File server 4

  3. Workload analysis Intranet applications (there different classes): • Corporate training: web based applicatin 2) Access to local file system

  4. Infrastructure hypothesis • All file server and web server have a single CPU and a single disk • The FDDI and the router are very fast versus the Lan Ethernet, then can be modelled as a simple delay, therefore they are server without queue • All the other components can be modelled as queues with service time independent by the load.

  5. User hypotheses • Finite number of users • An user generates a new request, after having received an answer to the previous request, after a time equal to its thinking time • 85% of users is working with the local file system • 15% of users is working with the Web Server

  6. Queueing network Multiclass closed queue model, each class is charaterized by: client group, application, server • client group: CLi: clients in Lan i (i: 1 to 4) • application: • FS for local file server access, • TR for Training • server: • FSi: i-th NFS server (i: 1 to 4) • WebS: Web Server

  7. Tipi di classi e numero di utenti (CL1, FS, FS1) 120 x 0.85 = 102 (CL2, FS, FS2) 50 X 0.85 = 43 (CL3, FS, FS3) 100 x 0.85 = 85 (CL4, FS, FS4) 100 x 0.85 = 85 (CL1, TR, WebS) 120 x 0.15 = 18 (CL2, TR, WebS) 50 x 0,15 = 7 (CL3, TR, WebS) 100 x 0,15 = 15 (CL4, TR, WebS) 100 x 0,15 = 15

  8. Server types Routers: low delay, given its low latency FDDI ring: low delay, given high bandwidth CPU Disks servers with load independ service time LANs Service Demands: Di,r = Vi,r x Si,r where Vi,r = Visit Ratio Si,r= Service Time

  9. QN model (CL1, FS, Fs1) (CL2,TR, Web) (CL2, FS, Fs2) (CL1, FS, Fs1) D D C D L2 C C (CL1, Tr, Web) R2 (CL2, Tr, Web) (CL3, FS, Fs3) (CL4, Tr, Web) L1 L3 R1 FDDI R3 R4 (CL1,TR, Web) (CL1,TR, Web) C (CL2,TR, Web) (CL3,TR, Web) Web S (CL4,TR, Web) D (CL3, TR, Web)

  10. Web server workload characterization(for a training session) • Avg request document size per HTTP request • 20 rqs for txt documents (2.000 bytes per doc) • 100 rqs for inline images (50.000 bytes each) • (20 text pages x 5 inline/text pages) • 15 rqs for other multi-media (mm) obj (2.000.000 bytes each)

  11. Web server workload characterization • % request for: • txt documents = 20/(20+100+15) = 15 % • inline images = 100/(20+100+15) = 74 % • other mm obj = 15/(20+100+15) = 11 %

  12. Web server workload characterization • Average document size 0.15 x 2.000 + 0.74 x 50.000 + 0.11 x 2.000.000 = = 257.300 bytes Note it is an average, the overhead associated to the three document sizes is different

  13. Web server workload characterization • Document request arrival rate is function of the think time and of the number of users in the system #Usersi (CLi, TR, Web) think time 18 per Lan 1 7 per Lan 2 15 per Lan 3 15 per Lan 4 45 sec Max # Usersi

  14. Web server workload characterization • Device service time • CPU: 1 msec processing time x HTTP request • Disk: We need to consider • Seekrand= avg time to position at a random cylinder • DiskRevTIme = time for a complete disk revolution • TransferTime = BlockSize/ 106 x TransferRate • ControllerTime = time spent at the controller for an I/O req. Sd = ControllerTime +Pmiss x (SeekRand + DiskRevolutionTime/2+TransferTime)

  15. Web server workload characterization • Lan hp: no fragmentation i.e. max data area 1500 bytes; hp no data overhead for HTTP request MessageSize + TCPOvhd NDatagrams = minn MTUn - IPOvhd Overheadn = TCPOvhd+Ndatagrams x (IPOvhd + FrameOvhdn) 8 x (MessageSize + Overheadn ) ServiceTimen = 106 x Bandwidth

  16. Web server workload characterization • Lan hp: no fragmentation i.e. max data area 1500 bytes; hp no data overhead for HTTP request • Ethernet 257300 + 20 NDatagrams = 1500- 20 Overheadn = 20 + Ndatagrams x (20 + 18) 8 x (257300 + 18 ) ServiceTimen = 106 x Bandwidth

  17. Web server workload characterization • Lan hp: no fragmentation i.e. max data area 1500 bytes; hp no data overhead for HTTP request • Token ring 257300 + 20 NDatagrams = 1500- 20 Overheadn = 20 + Ndatagrams x (20 + 28) 8 x (257300 + 28 ) ServiceTimen = 106 x Bandwidth

  18. Web server workload characterization • Router • delay 134 msec x packet (approximated in total to 1 msec) • FDDI • delay with 8 x (MessageSize + Overheadn ) ServiceTimen = 106 x Bandwidth

  19. Local file system workload characterization • File dimension 8192 bytes • avg NFS request arrival rate is function of the think time and number od users in the system #Usersi (CLi, FS, FSi) think time 10 sec 102 per Lan 1 43 per Lan 2 85 per Lan 3 85 per Lan 4 Max #Usersi

  20. Local file systemworkload characterization • Device service time • CPU: 1 msec per file request • Disk: We need to consider • Seekrand= avg time to position at a random cylinder • DiskRevTIme = time for a complete disk revolution • TransferTime = BlockSize/ 106 x TransferRate • ControllerTime = time spent at the controller for an I/O req. • N blocks to read = 8192/2048 = 4 • Lan i with 8192 bytes

  21. Throughput & response time Class Throughput Response time (req/sec) (sec) • CL1, FS, FS1 10,12 0,08 • CL2, FS, FS2 4,23 0,06 • CL3, FS, FS3 8,44 0,08 • CL4, FS, FS4 8,44 0,07 • CL1, TR, WebS 0,34 8,58 • CL2, TR, WebS 0,14 8,55 • CL3, TR, WebS 0,28 7,96 • CL4, TR, WebS 0,28 8,35

  22. Throughput & response time Max#Usersi Throughput = response time + think time

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